The invention relates to a control apparatus for precision-mechanical applications or for surgical applications, for example for use in endoscopes or the like.
More particularly, the invention relates to a control apparatus for instruments for high-precision mechanical applications or for surgical applications in the minimally invasive field.
Such control apparatuses are known from prior art and have a proximal end section, meaning an end section facing towards the user/surgeon, and an end section distal to or facing away from the user/surgeon, each of which comprises an articulation zone, and a central section which is arranged between said end sections and is frequently configured to be flexurally rigid. The control apparatuses further comprise an outer hollow-cylindrical shaft, an inner hollow-cylindrical shaft and a control element which is arranged between said shafts and has two or more force-transmitting longitudinal elements which extend substantially from the proximal to the distal end section of the control apparatus. The force-transmitting longitudinal elements are arranged substantially regularly in a circumferential direction of the control apparatus and are interconnected in the area of the proximal and the distal end sections thereof in each case in a circumferential direction. Via the longitudinal elements, tension and preferably also compression forces can be transmitted with which a pivotal movement of the proximal end section can be translated into a correlating pivotal movement of the distal end section.
Generally, the proximal end of the control apparatus described at the outset has mounted thereto a manually operated handle part which can, of course, be replaced by motor-driven operating elements, whereas the distal end, also referred to as a head, can have tools, cameras, illuminating elements and the like connected thereto.
With such instruments that incorporate the control apparatus, it is possible in the mechanical field to inspect and repair for example intricate and difficult-to-access interiors of for example engines, machines, radiators and the like, or, in the surgical field, to perform the above-mentioned operations utilizing minimally invasive techniques.
Control apparatuses of the type mentioned at the outset are known for example from WO 2005/067785 A1, which uses a multiplicity of force-transmitting longitudinal elements in the form of wires or cables that are arranged in direct contact with one another in a circumferential direction, thus guiding one another laterally. The outer and inner hollow-cylindrical shafts are available to provide for guidance of the force-transmitting longitudinal elements in a radial direction so that guidance of the force-transmitting longitudinal elements is ensured in each direction.
Working in a similar way, the control apparatuses disclosed in WO 2009/098244 A2 use a slotted tube as a control element instead of the cables or wires. The control element comprises a multiplicity of longitudinal elements defined by slots in the tube and held together by unslotted end portions of the tube.
For the function of the control element described in WO 2009/098244 A2, it is important for the longitudinal elements to be wire-shaped, and hence flexible, in the articulation zones of the control apparatus and to be resistant to bending in the central section interposed between the articulation zones.
While a control element fabricated out of a tube has certain advantages in assembly of the control apparatus, the slotted tube is, on the other hand, elaborate to manufacture, in particular because the central section of the longitudinal elements has to be flexurally rigid.
In the latter regard, the concept described in WO 2009/112060 is more advantageous in that it eliminates the need for the flexurally rigid central sections of the longitudinal elements. But here, too, the function of force transmission via the longitudinal elements requires that these be mutually laterally guided, and this is associated with the occurrence of additional frictional forces.
The control apparatuses known heretofore have, by virtue of their construction principle, the disadvantage that when actuated, frictional forces operate between the longitudinal elements which act to fatigue the user, for example, the surgeon, at least over prolonged periods of use. This is particularly disadvantageous because it puts the patient at risk.
It is an object of the invention to propose a control apparatus which allows the user to work over a prolonged period of time without fatigue.